Welding Systems Useful for Closure of Cardiac Openings

ABSTRACT

A welding element is provided for applying heat, chemicals, pressure, or any combination thereof to tissues inside a patient&#39;s body, e.g., a patent foramen ovale. In one aspect, the welding element is connected to a radio frequency energy source and includes an electrode and a locator. The locator facilitates positioning of the welding element and is capable of moving from an open position to a clamping position. In another aspect, a needle is provided for transseptal puncturing before the application of heat. In yet another aspect, the welding element is configured as a coil. The welding element can be made of Nitinol.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 13/189,438 filed Jul. 22, 2011, now pending; which is a divisionalapplication of U.S. application Ser. No. 11/044,657 filed Jan. 27, 2005,now issued as U.S. Pat. No. 7,988,690; which claims the benefit under 35USC §119(e) to U.S. application Ser. No. 60/540,827 filed Jan. 30, 2004,U.S. application Ser. No. 60/540,821 filed Jan. 30, 2004 and U.S.application Ser. No. 60/540,474 filed Jan. 30, 2004, all now expired.The disclosure of each of the prior applications is considered part ofand is incorporated by reference in the disclosure of this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to devices, systems, and related methodsfor closing cardiac openings through tissue welding. An exemplaryapplication of the invention can be found in closing a patent foramenovale.

2. Background Information

The human heart is divided into four compartments or chambers. The leftand right atria are located in the upper portion of the heart and theleft and right ventricles are located in the lower portion of the heart.The left and right atria are separated from each other by a muscularwall, the intraatrial septum, while the ventricles are separated by theintraventricular septum.

Either congenitally or by acquisition, abnormal openings, holes, orshunts can occur between the chambers of the heart or the great vessels,causing blood to flow therethrough. Such deformities are usuallycongenital and originate during fetal life when the heart forms from afolded tube into a four chambered, two-unit system. The deformitiesresult from the incomplete formation of the septum, or muscular wall,between the chambers of the heart and can cause significant problems.

One such deformity or defect, a patent foramen ovale, is a persistent,one-way, usually flap-like opening in the wall between the right atriumand left atrium of the heart. In the fetus, the foramen ovale serves asa conduit for right-to-left atrial shunting. After birth, with theestablishment of pulmonary circulation, the increased left atrial bloodflow and pressure results in functional closure of the foramen ovale.Normally, this is followed by anatomical closure of the two overlappinglayers of tissue at the foramen ovale: the septum primum and the septumsecundum. However, in certain individuals, a patent foramen ovale (PFO)persists. Depending on the method used to detect a PFO, an estimated 25to 35% of adults have PFO.

Because the left atrial pressure is normally higher than right atrialpressure, the flap in people with a PFO typically stays closed. However,under certain conditions, right atrial pressure exceeds left atrialpressure, creating the possibility for right to left shunting that canallow blood clots to enter the systemic circulation. Consequentially,paradoxical embolism via a PFO is being considered in diagnosing causesfor ischemic strokes, especially in young patients. Many studies haveconfirmed a strong association between the presence of a PFO and therisk for paradoxical embolism or stroke. In addition, there is goodevidence that patients with PFO and paradoxical embolism are atincreased risk for future, recurrent cerebrovascular events.

Patients suffering a stroke or transient ischemic attack (TIA) in thepresence of a PFO and without another apparent cause for ischemic strokeare considered for prophylactic medical therapy to reduce the risk of arecurrent embolic event. These patients are commonly treated with oralanticoagulants which have the potential for adverse side effects, suchas hemorrhage, hematoma, and adverse interactions with other drugs. Incertain cases, such as when anticoagulation is contraindicated, surgerymay be used to close a PFO. Under direct visualization, a surgeon cansuture together the septum secundum and septum primum with a continuousstitch.

Nonsurgical (i.e., percutaneous) closure of patent PFO, as well as othercardiac openings such as atrial septal defects and ventricular septaldefects, have become possible using a variety of mechanical closuredevices. Currently available closure devices, however, are often complexto manufacture and require a technically complex implantation procedure.Because they are mostly designed to close septal defects, which areactual holes different from the flap-like anatomy of PFO, the existingdevices lack more specific anatomic conformability for closing PFO andother similar cardiac openings.

Improved devices, systems, and related methods for closing cardiacopenings, such as PFO, are, therefore, needed.

SUMMARY OF THE INVENTION

The present invention provides devices, systems, and related methods forwelding tissues, i.e., fusing previously separate tissues together, atleast temporarily, through heat, chemicals, e.g., collagen orfibrinogen, pressure, or combinations of the above inside a patient asexemplified by procedures for closing cardiac openings. In one aspect,devices of the invention are configured to apply heat and/or pressure tothe target tissue such as tissues lining a cardiac opening. Anembodiment of this aspect of the invention can be found in anintravascular catheter that has an elongated sheath and a weldingelement located in the sheath's bore. The welding element is alsoextendable out of one of two ends of the sheath for deployment. Thewelding element includes an electrode and a locator. The locatorfacilitates proper positioning of the welding element inside a vascularsystem, and is capable of moving from an open position to a clampingposition. The locator may be attached to the distal end of the electrodeat an angle relative to the longitudinal axis of the electrode. Theangle can be acute, obtuse, or substantially perpendicular. The anglemay decrease, thus, moving from the open position to the clampingposition when connected to an energy source, e.g., a radio frequencyenergy source. Additionally, the locator may include a second electrodeor a balloon. The welding element may move between a deployedconfiguration and a retracted configuration. The welding element may beoperably attached to an elongated cable to help transition the weldingelement between the deployed configuration and the retractedconfiguration.

The electrode in the welding element may be flexible. The electrode maybe less than 1 mm in diameter. At least part of the welding element,e.g., the electrode(s) and/or the locator, may be made at least in partof Nitinol. In one embodiment, the welding element generates a clampingforce when the electrode is connected to an energy source. The weldingelement may be releasable. Additionally, the welding element maycomprise three electrodes or may comprise a coil. The welding elementmay also be capable of releasing welding agents to facilitate tissuereparation, e.g., fibrinogen, collagen, and/or an adhesive. Theintravascular catheter may also comprise a hollow needle disposed at afirst end of the elongated sheath.

In another aspect of the invention, for treatment of an intracardiacsite, the welding element includes a needle. Accordingly, anintravascular catheter that has an elongated catheter body, a hollowneedle, a distal tissue anchor, and an electrode is provided. The needlemay be used for transseptal puncturing. The catheter body has a proximalend and a distal end. The needle has a distal tip and a proximal end,and a bore extending from the distal tip towards the proximal end. Theneedle is disposed at the distal end of the catheter body. In oneembodiment, the needle is at least about 7 mm long. The distal tissueanchor is deployable from the distal end of the catheter body, e.g., inthe bore of the needle before being deployed. The distal tissue anchormay include a plurality of prongs. The electrode is disposed at thedistal end of the catheter body and connectable to an energy source,e.g., a source of RF energy. The catheter may also be capable ofreleasing welding agents to facilitate tissue reparation, e.g.,fibrinogen, collagen, and/or an adhesive.

The electrode may be located at various parts of the distal end of thecatheter body. It may comprise at least a portion of a wire thatslidingly deploys the distal tissue anchor from the bore of the needle.The electrode may also comprise at least a portion of the distal tissueanchor or the needle. The electrode may be made, at least partly, ofNitinol.

Further, a proximal anchor can be added to exert a force opposite thedistal anchor. The proximal anchor may include a plurality of prongs,each prong measuring less than about 6 mm. In one embodiment, theintravascular catheter may further include a second electrode deployedproximal to the distal tissue anchor. The proximal tissue anchor maycomprise at least a portion of the second electrode. The proximal tissueanchor may comprise the distal end of the catheter sheath.

In another aspect of the invention, the welding element is configured asa coil. Accordingly, an intravascular catheter that has a coil having aninsulated portion and uninsulated portion is provided where theuninsulated portion includes an electrode connectable to an energysource. The energized electrode provides heat to an intracardiac siterequiring treatment. The catheter may further include an elongatedsheath with a proximal end, a distal end, and defines a bore, where thecoil is extendable from inside the bore. In one embodiment, the coil hasa first pitch and a different second pitch. In one embodiment, at leastone of the first or second pitch decreases when the electrode isconnected to an energy source, e.g., a RF energy source, therebygenerating a clamping force. In another embodiment, both the first andsecond pitches decrease when the electrode is energized. In yet anotherembodiment, the coil is releasable from a distal end of the weldingelement, i.e., from the rest of the intravascular catheter.

In one embodiment, the first pitch of the coil measures between about 5mm and about 10 mm, e.g., for securing a patient's septum secundum, andthe second pitch measures less than about 1.5 mm, e.g., for securing apatient's septum primum. The coil may be made of a shape-memorymaterial, e.g., Nitinol. The coil may also be capable of releasingwelding agents, e.g., fibrinogen, collagen, and an adhesive.

In yet another aspect of the invention, a method for treating a patentforamen ovale in the heart of a patient is provided. The method includesintroducing an intravascular catheter into a patient's heart. Thecatheter includes an elongated sheath and a welding element disposedwithin the sheath's bore. The welding element is extendable out of oneend of the sheath's bore and includes an electrode and a locator. Thewelding element is extended between the patient's septum primum andseptum secundum in the heart. The locator is transitioned between anopen position and a clamping position to position the welding elementsuch that it contacts both the patient's septum primum and septumsecundum. Energy is then applied to the electrode to heat the patient'sseptum primum and septum secundum.

In another embodiment of a method for treating a patent foramen ovale inthe heart of a patient according to the present invention, anintravascular catheter is introduced into the patient's heart, thecatheter comprising a coil that includes an electrode. The coil isengaged with both the septum secundum and septum primum such that theelectrode contacts both the septum secundum and septum primum. Theelectrode is connected to an energy source to heat both the septumsecundum and septum primum. The method may include generating a clampingforce in the coil when the electrode is energized to keep the septumsecundum and septum primum in contact with each other during heating.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention.

FIG. 1A is a schematic view of an intravascular catheter with a weldingelement according to an illustrative embodiment of the invention.

FIG. 1B is a cross-sectional view of the system of FIG. 1A along theline 1B-1B.

FIGS. 2A, 2B and 2C are schematic side views illustrating how the systemof FIG. 1A is used to treat a patent foramen ovale according to anillustrative embodiment of the invention.

FIG. 3 is a side view of a welding element according to an illustrativeembodiment of the invention.

FIG. 4 is a partial cross-sectional view of an intravascular catheterwith a distal locator collapsed inside the catheter sheath according toan illustrative embodiment of the invention.

FIG. 5A is a partial cross-sectional view of the catheter of FIG. 4 withthe distal locator deployed outside the catheter sheath at an openposition, according to an illustrative embodiment of the invention.

FIG. 5B is a partial cross-sectional view of the catheter of FIG. 4 withthe distal locator deployed outside the catheter sheath at a clampingposition, according to an illustrative embodiment of the invention.

FIG. 6 is a schematic side view illustrating a PFO closure procedureusing the catheter of FIGS. 4 and 5 where the catheter sheath is beingpushed through the PFO tunnel to access the left atrium with its distalportion, according to an illustrative embodiment of the invention.

FIG. 7 is a schematic side view illustrating a step following FIG. 6where the locator of the catheter is fully deployed, according to anillustrative embodiment of the invention.

FIG. 8 is a schematic side view illustrating a step following FIG. 7where the locator rests against the tip of the septum primum, accordingto an illustrative embodiment of the invention.

FIG. 9 is a schematic side view illustrating a step following FIG. 8where the catheter is being withdrawn from the heart, according to anillustrative embodiment of the invention.

FIG. 10A is a side view of a welding element with a needle in a fullydeployed state, according to an illustrative embodiment of theinvention.

FIG. 10B is a cross-sectional view of the welding element of FIG. 10Ataken along the line 10B-10B.

FIGS. 10C and 10D are perspective side views of the welding element ofFIG. 10A in retracted states, according to an illustrative embodiment ofthe invention.

FIG. 10E is a side view of an alternative embodiment of FIG. 10A wherethe needle is separate from the proximal anchor.

FIG. 11 is a side view of an embodiment of the welding element with aneedle in a deployed state, according to the invention.

FIGS. 12A and 12B are perspective side views of the welding element ofFIG. 11 where the distal locator is in retracted states, according to anillustrative embodiment of the invention.

FIG. 13 is a side view of an embodiment of the welding element where thedistal locator resembles a fork, according to the invention.

FIG. 14 is a schematic side view illustrating a PFO closure procedureusing the catheter depicted in FIGS. 10A-10D where the needle penetratesboth the septa secundum and primum, according to an illustrativeembodiment of the invention.

FIG. 15 is a schematic side view illustrating a step following FIG. 14where both the distal anchor and the proximal anchors are deployed,according to an illustrative embodiment of the invention.

FIG. 16 is a schematic side view illustrating a step following FIG. 15where heat is applied through a portion of the needle in the weldingelement, according to an illustrative embodiment of the invention.

FIG. 17A is a schematic side view illustrating an alternative stepfollowing FIG. 14 where heat is applied through a portion of a cablethat supports the distal anchor, according to an illustrative embodimentof the invention.

FIG. 17B is a schematic side view illustrating a method for using theembodiment depicted in. FIG. 12B.

FIG. 17C is another side view normal to the view depicted in FIG. 17B,according to an illustrative embodiment of the invention.

FIG. 18 is partial cross-sectional view of a catheter sheath with a sideview of a coiled welding element disposed inside the sheath, accordingto another illustrative embodiment of the invention.

FIG. 19A is a side view of the illustrative welding element of FIG. 18with the coil deployed, according to an illustrative embodiment of theinvention.

FIG. 19B is a top view of the welding element depicted in FIG. 19A.

FIG. 20 is a schematic side view illustrating a PFO closure procedureusing the catheter depicted in FIGS. 18, 19A, and 19B where the coil isdeployed in the left atrium, according to an illustrative embodiment ofthe invention.

FIG. 21 is a schematic side view illustrating a step following FIG. 20where the coil engages both the septa secundum and primum, according toan illustrative embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to devices, systems, and related methodsfor heating tissues inside a patient's body, e.g., for closing cardiacopenings such as a PFO tunnel. A welding element is provided forapplying heat and/or pressure to cardiac tissues. An exemplaryapplication for the welding element is to fuse the septum primum to theseptum secundum, thereby closing the PFO tunnel. In one aspect of theinvention, a locator is provided for proper positioning of the weldingelement. In another aspect, a puncturing means is provided in thewelding element. In yet another aspect of the invention, the weldingelement is shaped in a coil. Any of these and other aspects of theinvention can be combined.

Referring to FIG. 1A, an exemplary percutaneous hansluminal system 10can be used for closing a cardiac opening. The system 10 includes awelding element 12 at a distal end of a carrier or delivery device, suchas any suitable type of catheter 14. For example, if the catheter 14 isto be used to access the heart from a femoral site, it will typicallyneed a length between about 80 to about 140 cm. In one embodiment, thecatheter 14 has an elongated sheath 18 with a distal end 20 and aproximal end 22. The sheath 18 may also include a radio-opaque marker19, e.g., a metal ring, at a desired location on the catheter, e.g., thecatheter distal end 20. The catheter 14 may include additional channelsfor optional functions, such as irrigating the welding site with afluid, a drug solution or an agent. Such constructions are well known inthe art of transluminal devices.

With continued reference to FIG. 1 A, the welding element 12 isconnectable to an energy source, e.g., a radio frequency (RF) source 16.A switch 17 maybe included to control the connection. Other energysources include, and are not limited to, AC (other than RF) or DCelectricity and so on. Heat at the welding element 12 can be generatedthrough radio frequency or other means, e.g., resistance heating. Theentirety or part(s) of the welding element 12 may generate heat, e.g.,by acting as electrodes connected to a source of electric current. Inone embodiment, at least part-of the welding element 12 is flexible orsemi-flexible, i.e., can be bent or flexed without permanent damage thatcompromises its functionality (e.g., visible fracture). In a preferredembodiment, at least a portion, e.g., a body portion 15, of the weldingelement 12 can be bent into or assumes, e.g., upon heat activation, aconfiguration that conforms to the anatomical shape or contour of thePFO, such that the welding element 12 can contact both the septum primumand septum secundum at the same time. Such a configuration enables theapplication of heat and/or pressure to both the septum primum and septumsecundum at the same time, and is advantageous in non-surgical treatmentof PFO. In one embodiment, the welding element 12 is made of ashape-memory material such as Nitinol that assumes the desiredconfiguration once connected to an energy source and reaches a certaintemperature.

Still referring to FIG. 1 A, the welding element 12 may include one ormore electrodes (not shown). In the embodiment where there is only oneelectrode in the welding element 1.2, a second reference electrode(ground) connected to the energy source may be placed on the patient'sthighs or other suitable areas. Parts of the welding element 12 thatwill likely contact blood during its operation may be insulated. Forexample, a distal portion 23 of the welding element 12 may be insulated(not shown). There are a variety of ways to insulate an otherwiseconductive body, e.g., with a non-conductive sleeve or coating, orembedding a non-conductive barrier between the insulated portion and theuninsulated portion. In other words, the insulated and uninsulatedportions can be made essentially of the same material but somehowsectionalized to be selectively heat-conductive when the welding element12 is energized. In one embodiment, a non-thrombogenic polymer halfsleeve or foam coating is applied for insulation purposes.

With reference to FIG. 1A, the welding element 12 is carried by anelongated cable 24 at its distal end 25. As best illustrated in FIG. IB,the elongated cable 24 slidingly extends inside a bore 26 defined by thecatheter sheath 18. The welding element 12 may stay inside the bore 26until it has been delivered to the desired anatomical location, e.g.,close to the septum secundum. In one embodiment, referring to FIG. 1A,the RF source 16 is connected to a proximal end 28 of the carrying cable24 and RF energy is supplied through an electric cable (not shown)insulated inside the carrying cable 24 to the electrodes(s) at the cabledistal end 25. Alternatively, there maybe other means and associatedfeatures for delivering and heating the welding element 12 as known toone skilled in the art of transluminal devices.

FIGS. 2A-2C depict how the device of the invention can be used to heatthe tissue, e.g., to close a cardiac opening. In this example, the leftatrium 30 and the right atrium 32 are shown to be separated by theseptum primum 34 and septum secundum 36. A PFO 38 is shown as the spacebetween the septum primum 34 and septum secundum 36. To access the PFO38, the catheter 14 is advanced through the patient's skin into a bloodvessel, e.g., through a standard femoral vein catheterization procedure.Other ways to access the heart, e.g., through the left atrium 30, mayalso be used. A guidewire 39 is typically used to facilitate theprocedure.

Referring first to FIG. 2A, the guidewire 39 first accesses the rightatrium 32 through the inferior vena cava 40, and progresses to the PFO38 by travelling between the septum primum 34 and the septum secundum 36until it accesses the left atrium 30. A dilator 43 may be passed overthe guidewire 39 to temporarily dilate the PFO 38. The catheter 14follows the same route and is threaded over the guidewire 39 to travelthrough the inferior vena cava 40, the PFO 38, until it reaches the leftatrium 30 as shown in FIG. 2B.

Referring to FIG. 2B, the operator withdraws the guidewire 39 and, inits place, advances the carrying cable 24 through the bore of thecatheter sheath 18 until the welding element 12 is delivered to the leftatrium 30 and deployed outside the sheath distal end 20. Referring nowto FIG. 2C, the operator then withdraws the catheter sheath 18 into theright atrium 32, and the welding element 12 into PFO 38 so that thewelding body portion 15 is positioned in between the septum primum 34and septum secundum 36. Depending on the structure of the weldingelement 12, its distal portion 23 may be exposed to blood in the leftatrium 30. In that case, the distal portion 23 is preferably insulatedso that it will not heat up blood during operation.

Referring to FIG. 2C, after confirming correct positioning of thewelding element 12, e.g., under fluoroscopy or echocardiography orthrough the use of a locator described below, the operator switches onthe switch 17 to connect the welding element 12 to the RF source 16.Consequently, heat is applied, through the electrode in the weldingelement 12, e.g., the welding body portion 15, to both septum primum 34and septum secundum 36. Alternatively, the body portion 15 may makecontact and apply heat to one of the septum primum 34 and septumsecundum 36 before repositioning to make contact and apply heat to theother. The electrode, in this case, the welding body portion 15 causesthe tissue to reach temperatures above 50° C., and in some cases, up toabout 100° C. The high temperature causes tissue cells to die in thevicinity of the welding element 12. The heat along with the pressuredifferential between the atria 30 and 32 causes the septa to fuse andthe PFO tunnel 38 to close. Welding agents and welding enhancingproducts, such as those encouraging or facilitating coagulation, tissuereparation, or wound healing, e.g., fibrinogen, or a bio-absorbablematerial such as collagen, can also be applied to the welding site,e.g., through a channel (not shown) inside the catheter 14 or through acoating on the welding element 12. The distal portion 23 and other partsof the welding element 12 that are exposed to blood are preferablyinsulated to prevent overheating the blood.

With continued reference to FIG. 2C, after a weld is created between theseptum primum 34 and the septum secundum 36, the welding element 12 ispulled out of the tissue weld. And the operator removes the catheter 14from the patient. Alternatively, if withdrawing the welding element 12completely out of the weld will cause too much damages to the tissue, aportion of or the entire welding element 12 may be left in the tissue.In one preferred embodiment, for example, a portion of the weldingelement 12 is detachable from the carrying cable 24 at a detachment site63. Such portion of the welding element 12 needs to be biocompatible tobe left inside the patient.

FIG. 3 depicts an illustrative embodiment of the welding elementaccording to the principle of the present invention. A welding element44, disposed at the cable distal end 25, includes one or moreelectrodes, e.g., three electrodes 46 a, 46 b, and 46 c. Each of theelectrodes 46 a, 46 b, and 46 c has a body portion 48 that is notinsulated and capable of heating any contacting tissue. Preferably, eachof the electrodes 46 a, 46 b, and 46 c also includes an insulatedportion 50, e.g., at their respective free end where they will likelycontact blood during operation. The insulated portion 50 avoids heatingup the blood in the heart compartments.

With continued reference to FIG. 3, the electrodes 46 a, 46 b, and 46 ccan be made of a variety of metals and alloys, such as steel, or copper.In one embodiment, they are made of Nitinol, which is a shape-memoryalloy. In one embodiment, the electrodes are flexible or semi-flexible.The electrodes 46 a, 46 b, and 46 c preferably assume a configurationcompatible to the anatomical shape of the site of treatment, e.g., thePFO. In one embodiment, the electrodes 46 a, 46 b, and 46 c are curvedsuch that, when placed in the PFO, the electrode body portion 48contacts both the septum primum and secundum at the same time.Alternatively, the electrodes 46 a, 46 b, and 46 c can be bent orinduced into such a configuration. In one embodiment, the electrodes 46a, 46 b, and 46 a are made of a shape-memory material such as Nitinol.

The electrodes 46 a, 46 b, and 46 c can be made with a relatively thinprofile. In one embodiment, the diameters of the electrodes 46 a, 46 b,and 46 c are less than about 1 mm. With such small diameters, theelectrodes 46 a, 46 b, and 46 c can be pulled out of the weld withoutsubstantial damage to the weld.

FIGS. 4 through 9 depict another illustrative embodiment of the weldingelement and related method of use according to the principle of theinvention. FIG. 4 depicts the embodiment in a collapsed or retractedconfiguration while FIGS. 5A and 5B depict the same embodiment indeployed configurations. Specifically, the embodiment is in an openposition in FIG. 5A, and in a clamping position in FIG. 5B. FIGS. 6through 9 depict steps in an illustrative method for using theembodiment depicted in FIGS. 4, 5A and 5B. Specifically, the method isused for closing the PFO but can be extended to other applications.

Referring to FIG. 4, an exemplary welding element 55 is joined to adistal end 60 of an elongated carrying cable 58. The carrying cable 58slidingly extends inside a bore 62 defined by a catheter sheath 64. Thewelding element 55 includes at least two portions: a body portion 66 anda locator 68. In one embodiment, the locator 68 is joined to the bodyportion 66 at its distal end 70. In another embodiment (not shown), thelocator 68 is joined to the proximal end of the welding body portion 66.The locator 68 may be shaped as one or more rods, disks, or any otherobjects that facilitate the proper positioning of the welding element55. The locator 68 may include an inflatable portion such as a balloon(not shown).

Still referring to FIG. 4, before deployment, the welding element 55 iscollapsed such that its body portion 66 and the locator 68 are foldedtogether to be substantially inside a distal end 71 of the sheath bore62. Now referring to FIG. 5A, after placing the sheath distal end 71 atthe desired location inside the body, e.g., in the left atrium, theoperator can deploy the welding element 55, e.g., by pushing the cableproximal end 72 in the distal direction so that the welding element 55extends outside of the sheath distal end 71. When the operator pulls thewelding element 55 back toward the sheath 64, the locator 68 is forcedby the sheath distal end 71 to straighten out and to generally alignwith the longitudinal axis of the welding body portion 66, similar tothe configuration shown in FIG. 9. The operator can subsequentlywithdraw the straightened welding element 55 into the sheath bore 62.

As depicted in FIG. 5 A, once outside the distal end 71 of the sheath64, the welding element 55 opens up into its deployed configuration. Inone embodiment, the locator 68 pivots away from the welding body portion66 when deployed. A variety of mechanisms can be used to effect thepivot, for example, by having a spring, coil, or shape-memory materialat the juncture between the welding body portion 66 and the locator 68.The welding body portion 66 may include one or more electrodes forgenerating heat. For example, the welding body portion 66 can be made ofa metal or metal alloy such as Nitinol. The locator 68 can be anintegral extension of the welding body portion 66 that is insulated. Forexample, the locator 68 may be made with or coated with a non-conductivematerial, e.g., a polymeric material. In one embodiment, both thewelding body portion 66 and the core of the locator 68 are one piece ofNitinol, which tends to assume a pre-selected configuration, e.g., ahook, that is advantageous for an intended function once it reaches atemperature range such as from the room temperature to the bodytemperature, e.g., from about 25° C. to about 35° C.

Alternatively, the locator 68 and the welding body portion 66 can beseparately manufactured and then joined together. Additionally, thelocator 68 may include an electrode 69 connected to an energy source,e.g., and RF energy source. The electrode 69 may facilitate the locator68 to change shape and to assume a pre-selected configuration orposition. The electrode 69 may also aid in the welding function of thedevise. For example, the electrode 69 may work in concert with anotherelectrode in the welding body portion 66 to heat the tissue in betweenthe electrodes. Alternatively, the electrode 69 may function as the soleelectrode in the welding element 55.

Still referring to FIG. 5A, in the deployed configuration, the locator68 initially forms, in an open position, an angle 74 a with thelongitudinal axis of the welding body portion 66. Such a hookedconfiguration allows the operator to retain the septum primum inside thehook, and therefore be sure of the position of the welding element 55before turning on the heat. In that sense, the locator 68 serves as apositional marker useful for avoiding heating an unintended target. Theopen angle 74 a can be obtuse, substantially perpendicular or acute,i.e., the open angle 74 a is in the range of 0 to 180 degrees,preferably 45-90 degrees. In one embodiment, the open angle 74 a isselected such that the deployed welding element 55 fits snugly over thetip of the septum primum 34.

Referring now to FIG. 5B, in one embodiment, at least the joint 75between the welding body portion 66 and the locator 68 is made of ashape-memory material, e.g., Nitinol. With shape memory materials, in aclamping position, a clamping angle 74 b between the locator 68 and thelongitudinal axis of the welding body portion 66 gets narrower as thetemperature changes to generate a clamping force against any tissuebetween the locator 68 and the welding body portion 66. One way tofacilitate switching the locator 68 from the open position to theclamping position is to position the heat-generating electrode close tothe joint 75, or making the joint 75 part of the electrode, so that itsshape-memory material is heated up quickly.

Referring specifically to FIG. 6, in an illustrative method for closinga PFO tunnel 38 using the embodiment described in FIGS. 4, 5A and 5B,the distal portion of the catheter sheath 64 is passed over a guidewire69 and advanced through the inferior vena cava 40, the PFO 38, until itsdistal end 71 reaches the left atrium 30, in a way similar to what isdescribed in connection with FIG. 2A. Then the guidewire 69 is withdrawnfrom the bore of the catheter sheath 64 and the welding element 55 isadvanced, through its carrying cable 58, in the catheter bore 62 (FIG.4) to the sheath distal end 71.

Referring to FIG. 7, once the welding element 55 reaches the left atrium30, the operator advances it out of the sheath distal end 71 to deploythe welding element 55. Consequently, the locator 68 opens to its fullydeployed configuration depicted previously in FIG. 5A, pivoted away fromthe welding body portion 66 at the open angle 74 a. Referring now toFIG. 8, the operator then pulls the deployed welding element 55 towardthe septum primum 34 until he or she senses resistance in movement,which indicates that the welding element 55 is resting against the tipportion 76 of the septum primum 34. Other configurations of the weldingelement 55 that facilitates the proper positioning of the welding bodyportion 66 in the PFO tunnel 38 between the septum primum 34 and theseptum secundum 36 are also contemplated by the present invention. Afterthe operator visually confirms the proper positioning, heat is appliedthrough the welding element as described earlier, and the clamping angle74 b gets narrower, generating a clamping force. In a preferredembodiment, the core of substantially the entire welding element 55 ismade of a shape memory material, e.g., Nitinol. The clamp force works inaddition to the existing pressure differential between the atria toforce the septum primum 34 and the septum secundum 36 against each otherduring and after the welding.

Referring to FIG. 9, after welding, the operator disconnects theelectricity from the welding element 55, which reduces its clampingforce. The operator can simply pull the welding element 55, e.g., bypulling its carrying cable 58 (FIG. 4), in the proximal direction tostraighten out the welding element 55, as illustrated here, beforepulling it out of the heart tissues.

According to another aspect of the invention, some embodiments of theinvention include a puncturing structure, e.g., a needle. The puncturingstructure is useful in a variety of applications, e.g., transseptalpuncturing. Referring to FIG. 10A, in an illustrative embodiment, awelding element 79 includes a hollow needle 80 that has a sharp distaltip 82, an opposite, proximal portion 84, and a bore 96 (bestillustrated in FIG. 10B) extending from the distal tip 82 towards theproximal portion 84. In this particular embodiment, the needle distaltip 82 is beveled, but other shapes useful for puncturing tissue arealso contemplated by the present invention. The needle proximal portion84 is joined to a needle-carrying cable 86 that slidingly extends insidea bore 88 defined by a catheter sheath 90. By moving the needle-carryingcable 86, the operator can slide the needle 80 in and out of a distalend 94 of the catheter sheath 90 between a deployed configurationillustrated in FIG. 10A and a retracted configuration illustrated inFIG. 10C.

Still referring to FIG. 10A, an optional proximal anchor or locator 127is attached to the needle 80. The proximal anchor 127 facilitates theproper positioning of the welding element 79. The proximal anchor 127may have one or more proximal anchor prongs 102 a and 102 b. The freeends 104 a and 104 b of the proximal anchor prongs 102 a and 102 b,respectively, extend generally away from the proximal portion 84 of theneedle 80 in the distal direction, i.e., toward the needle distal tip82. The distal tips 104 a and 104 b of the proximal anchor prongs 102 aand 102 b, respectively, maybe sharp or blunt. The proximal anchor 127may assume a variety of shapes, e.g., a stop ring (not shown), thatassist in anchoring the needle 80 against a target tissue. In theembodiment illustrated in FIG. 10A, the proximal anchor 127 has proximalanchor prongs 102 a and 102 b which resemble prongs of a fork. Moregenerally, the proximal anchor 127 may serve to immobilize the entirety,or part, of the welding element 79. In that sense, the proximal anchor127 may serve the function akin to the locator 68 described above inother embodiments and help to facilitate the proper positioning of thewelding element 79, for example, by acting as a proximal stopper againstfurther advance of the needle 80. The needle 80 and the proximal anchor127 may be manufactured as an integral piece and made of the samematerial such as a metal or metal alloy, e.g., Nitinol, or separately.

Referring briefly to FIG. 10C, to retract the proximal prong 127 intothe catheter sheath 90, the operator may force the proximal anchorprongs 102 a and 102 b against the sheath distal end 94 into a collapsedor otherwise compact configuration as he pulls the needle 80, throughthe needle-carrying cable 86, into the catheter sheath bore 88.

Referring back to FIG. 10A, a central cable 98, carrying a distal anchoror locator 100 is slideably positioned within the needle bore 96. Thespatial relationship between the catheter sheath 90, the needle 80, andthe central cable 98 is illustrated in FIG. 10B. The distal anchor 100also can switch between a deployed configuration illustrated in FIG. 10Aand a retracted or collapsed configuration illustrated in FIGS. 10C and10D. The distal anchor 100 may assume any of many desired configurationsand shapes that facilitate anchoring the needle 80 against the targettissue. The distal anchor 100 serves to immobilize the entirety, orpart, of the welding element 79. The distal anchor 100 may serve afunction akin to the locator 68 described above in other embodiments andhelp to facilitate the proper positioning of the welding element 79, forexample, by acting as a distal stopper against further advance of theneedle 80. In one embodiment, the distal anchor 100 can resemble thelocator 68 with the ability to move from an open position to a clampingposition, generating a clamping force.

Still referring to FIG. 10A, in the illustrated embodiment, the distalanchor 100 includes one or more prongs 106 a and 106 b that are joinedto a distal end 108 of the central cable 98. The prong tips 107 a and107 b both pivot away from the central cable 98 in the deployedconfiguration through a spring, a coil, a shape-memory material, orother mechanism known to one skilled in the art. In one embodiment, theprongs 106 a and 106 b both curve backward in the deployedconfiguration, and the prong tips 107 a and 107 b are sharp for engagingtissue. The distal anchor 100 may be made of any suitable material suchas a metal or metal alloy, e.g., Nitinol.

Referring to FIG. 10C, to deploy the distal anchor 100 from theretracted configuration, the operator pushes the central cable 98 in thedistal direction to extend the distal anchor 100 out of the needle tip82, which then expands into its deployed configuration depicted in FIG.10A. Referring to FIG. 10D, to retract the distal anchor 100 back intothe needle 80, the operator simply pulls the central cable 98 in theproximal direction while holding the needle-carrying cable 86 fast. Theoperator can force the prongs 106 a and 106 b to bend forward againstthe needle distal tip 82 in order to collapse them into the needle 80.

Referring back to FIG. 10A, the welding element 79 includes at least oneelectrode for applying heat to the target anatomical structure. In oneembodiment, the entirety or part of the needle 80, e.g., an exposedmiddle portion 110 (with the rest of the needle 80 insulated), serves asan electrode. In another embodiment, an exposed portion 112 of thecentral cable 98 (with the rest of the central cable 98 insulated),serves as an electrode. In yet another embodiment, the entirety or partof the distal anchor 100 and/or the proximal anchor 127 serves as theelectrodes. The proximal anchor 127 can also be used as a secondelectrode, so that electric current, e.g., AC, travels between thedistal anchor 100 and the proximal anchor 127. Surfaces of the distalanchor 100 and proximal anchor 127 that will contact blood can beinsulated through the application of a non-conductive, non-thrombogeniccoating or sleeve (not shown), e.g., a polymeric half sleeve or a foam.Where the welding element 79 has only one electrode, a second referenceelectrode may be placed elsewhere on the patient body.

Referring now to FIG. 10E, in an alternative embodiment of theinvention, the distal anchor 100 may have electrodes 155 a and 155 b onthe distal anchor prongs 106 a and 106 b, respectively. The proximalanchor prongs 102 a and 102 b may also have electrodes 157 a and 157 b,respectively, so that electric current, e.g., alternating current (AC),travels between the distal anchor electrodes (155 a and 155 b) and theproximal anchor electrodes (157 a and 157 b). In another embodiment,electric current can travel between the proximal electrodes (157 a and157 b) and an electrode 110 on the needle 80. In another embodiment,electric current can travel between the distal anchor electrodes (155 aand 155 b) and the electrode 110 on the needle 80. In yet anotherembodiment, only a single electrode, for example, any of the electrodes155 a, 155 b, 157 a, 157 b, or 110, is used.

Still referring to FIG. 10E, in the illustrated embodiment, the needle80 is manufactured separately from the proximal anchor 127 such that theneedle 80 and proximal anchor 127 can slide independent of each other.The proximal anchor 127 is joined to a second carrying cable 131. Theneedle 80 is slidingly disposed within a bore 129 in the proximal anchor127. This alternative embodiment may include other features described inconnection with other embodiments.

Referring to FIG. 11 in one embodiment of the invention, a weldingelement 120 includes a hollow needle 122 similar to the needle 80described above, and parts of the welding element 120 also move betweendeployed and retracted configurations by virtue of axial movement of aneedle-carrying cable 126 and a central cable 134. The needle 122, whichhas a sharp distal tip 124, is joined to the needle carrying cable 126and therefore slidingly extends inside a bore 128 defined by a cathetersheath 130. A distal anchor 132, disposed at a distal end of the centralcable 134, slidingly extends inside a needle bore 136 and is depicted inits deployed configuration in FIG. 12A. In the depicted embodiment, thedistal anchor 132 assumes a largely planar and round surface.

Referring to FIGS. 12A and 12B, the distal anchor 132 of welding element120 in the embodiment depicted in FIG. 11 can assume a collapsed orotherwise compact configuration inside the needle bore 136.

Specifically Referring to FIG. 12A, to deploy the distal anchor 132 fromits retracted configuration, the operator pushes the central cable 134to force the distal anchor 132 out of the needle distal tip 124, and thedistal anchor 132 expands into its deployed configuration illustrated inFIG. 11. Referring now to FIG. 12B, to retract the distal anchor 132,the operator pulls the central cable 134 away from needle tip 124 whileholding the needle carrying-cable 126 fast. The operator can force theplanar surface of the distal anchor 132 to flip against the needledistal tip 124 in order to collapse into the needle. One or moreproximal anchor or locator (not shown) may be optionally attached to aportion of the needle 122. The electrode(s) of the welding element 120may be an exposed portion 138 of the needle 122, or the distal anchor,or the proximal anchor or a combination thereof.

Referring to FIG. 13, in another embodiment of the invention, a distalanchor 133 includes prongs 135 arranged like a fork. An optionalproximal anchor 137 is associated with the needle 122 in a mannersimilar to that described above in connection with FIG. 10A.

FIGS. 14 through 17C depict steps in an exemplary method using anyembodiment of the invention with a puncturing structure to close acardiac opening, e.g., a PFO tunnel. Using the embodiment depicted inFIG. 10A as an example and referring first to FIG. 14, the operatoraccesses the heart as described previously, e.g., through the inferiorvena cava 40 to the right atrium 32 with the welding element 79 (FIG.10G) retracted inside the catheter sheath 90. Once the operatorconfirms, e.g., through real time 3D echocardiography, that the catheterdistal end 94 reaches the septum secundum 36, he can deploy the needle80 by sliding it out of the catheter distal end 94 into the septumsecundum 36, preferably into the secundum tip portion 41. The averagethickness of septum secundum 36 is about 6 mm to about 10 mm, and about1 mm for septum primum 34. In a preferred embodiment, the needle 80 isfrom about 6 mm to about 15 mm so that its distal tip 82 not onlypenetrates the septum secundum 36 but also the septum primum 34.

Referring to FIG. 15, the operator slides the distal anchor 100 out ofthe needle distal tip 82 and the distal anchor 100 expands into itsdeployed configuration with prongs 106 a and 106 b curving backward. Theoperator can then extend the needle 80 further out of the catheterdistal end 94 so that the proximal anchor prongs 102 a and 102 b are outof the catheter sheath 90 and expand into the deployed configuration.The proximal anchor prongs 102 a and 102 b engage the septum secundum 36with their fork-like configuration.

Referring to FIG. 16, with the proximal anchor prongs 102 a and 102 bstabilizing the septum secundum 36, the operator pulls the distal anchor100 in the proximal direction until it rests against the septum primum34 or otherwise engages the septum with the prong tips 107 a and 107 b.As a result, the operator uses opposite forces to clamp the septasecundum 36 and primum 34 together beyond what is provided by the atrialpressure differential. In embodiments without a particular structure forproximal anchor, the operator can substitute the proximal anchor withthe distal end 94 of the catheter sheath. The above steps can besimilarly performed from the left atrium 30 as well, i.e., puncturingthe septum primum 34 and then the septum secundum 36.

After both the proximal anchor prongs 102 a and 102 b, and the distalanchor 100 have been deployed to clamp the septum primum 34 and septumsecundum 36 together, the operator may turn on the electrode(s) in thewelding element 79 to apply heat to both the septum primum 34 and septumsecundum 36. In one embodiment, the electrode is the middle section 110of the needle 80. The needle middle section 110, in the position shownin FIG. 16, contacts both the septum primum 34 and septum secundum 36,and is not exposed to blood in the atria. In another embodiment, theelectrodes are the distal anchor 100 and/or proximal anchor 127. Theelectrodes can be used to provide heat energy by themselves or incombination with the middle section 110 of the needle 80. Additionally,more than one puncture can be created across the septum primum 34 andthe septum secundum 36 by repeating the above steps.

In another embodiment, where the proximal anchor 127 and/or distalanchor 100 is/are made of a shape-memory material, the heat created bythe electrodes causes the proximal and/or distal anchor to stiffen andexert further clamping force, pushing the septum primum and septumsecundum further against each other during the welding. In other words,the angle of the deployed anchors changes upon heat activation tofurther clamp the septum primum and septum secundum together.

After a weld is created between the septum primum 34 and septum secundum36, the operator withdraws the distal anchor 100 into the needle 80. Theoperator also withdraws the proximal anchor 127 into the catheter sheath90. Then the operator withdraws the needle 80 and the catheter sheath 90out of the patient. The septal puncture left by the needle 80 heals overtime.

Referring to FIG. 17A, in a method using an alternative embodiment wherethe electrode is part of the central cable 98 supporting the distalanchor 100, the distal anchor 100 is deployed and engages the septumprimum 34 as described above following the step depicted in FIG. 14. Theneedle 80 (shown in FIG. 14) is retracted into the catheter sheath 90.Instead, to clamp the septa together, the operator uses the catheterdistal end 94 to push the septum secundum 36 while pulling the septumprimum 34 using the distal anchor 100. The exposed portion 112 of thecentral cable 98 is in contact with both septum primum 34 and septumsecundum 36. Therefore, the operator can apply energy (e.g., RF) to weldthe septa together.

Referring to FIGS. 17B and 17C, in an alternative embodiment, theelectrode in the welding element is at least a portion of the distalanchor, e.g., its proximal surface, when deployed, that contacts theseptum primum 34 and the septum secundum 36. Using the embodimentdepicted in FIG. 12 as an example, the distal anchor 133 is pulled backagainst the septum primum 34 and the septum secundum 36 with itsmultiple prongs 135. The optional proximal anchor 137 may be employed toexert an opposing force in order to force the septum primum 34 againstthe septum secundum 36. The distal anchor 133 may be used as a singleelectrode that applies heat to yield several weld joints along thelength of the PFO, similar to usage of interrupted sutures, or it may beused in combination with another electrode located on either theproximal anchor 137 or the middle portion 110 of the needle 80. Theanchor's distal surface 139 is preferably insulated. The operator maypuncture the septum primum 34 and septum secundum 36 at variouslocations along the PFO, and depending on the amount of electricity andheat applied, creating welds of various sizes. While the PFO may not besealed along its entire length by a single weld, two to ten welds withrelatively small intervals can be created in this fashion. These weldsmay not overlap at all, or overlap among some of them, or even overlapto effectively form one continuous weld. This is one approach toeffectively seal off the PFO and to reduce risks of embolus resultingfrom blood flow from right to left atria.

FIGS. 18,19A and 19B depict embodiments of the invention that include acoil in the welding element. By coil, it is meant to includeconfigurations that resemble a spiral or helix where thethree-dimensional locus of a point in the configuration moves parallelto and about a central axis at a constant or varying distance. Suchconfigurations are also commonly noted as a helix, spiral, twist, orcurl. FIG. 18 depicts a cross-sectional view of a welding element .150inside a catheter sheath 152. The welding element 150 includes a coil153 joined to a carrying cable 154, which in turn slidingly extendsinside the bore 156 of the catheter sheath 152. The coil 153 may be madeof any suitable materials such as metals, alloys or plastic. In onepreferred embodiment, the coil 153 is made of Nitinol.

FIGS. 19A and 19B depict, from the side and top views respectively, thedeployed coil 153 outside the catheter sheath 152, e.g., when theoperator twists the carrying cable 154 in one direction or simply pushesthe carrying cable in the distal direction. The coil 153 typicallyexpands in its diameter when deployed. Using a material such as Nitinolthat has shape memory allows the operator to pre-select the shape anddimension of the coil 153 inside the heart, where the range oftemperature is predictable. In one embodiment, the deployed coil 153includes about one and a half turns, which can be divided into threeportions in the helical structure. From a coil distal tip 157 to ahalf-turn point 158 down the coil is a distal section 159. From thepoint 158 to the next half-turn point 160 down the coil is a middlesection 162. From the point 160 to the next half-turn point 164 down thecoil is a proximal section 166. Of course, the coil 153 may have more orfewer turns than described by these three sections.

In the deployed state, the distance between the distal tip 157 and itscorresponding point 160 one turn down the coil is a distal pitch 168.The distance between the point 158 and its corresponding point 164 oneturn down the coil is a proximal pitch 170. In a preferred embodiment,the distal pitch 168 is such that at least the tip potion of a septumprimum can fit between the distal tip 157 and its corresponding point160. In other words, the distal pitch 168 is at least about 0.1 mm, andpreferably less than about 4.0 mm. In a preferred embodiment, the distalpitch 168 is about 1 mm. The proximal pitch 170 is such that at leastthe tip potion of a septum secundum can fit between the point 158 andits corresponding point 164. In other words, the proximal pitch 170 isat least about 5 mm, and preferably between about 6 and about 20 mm.

The coil 153 may include an insulated portion and an uninsulatedportion. The surface of the insulated portion does not heat upsignificantly when the coil 153 is energized while the uninsulatedportion does. There are a variety of ways to have portions of the coil153 differ in terms of heat conductivity. In one embodiment, theinsulated portion is not connected to the source of energy and is madeof a material with low heat conductivity, e.g., a polymeric material,while the uninsulated portion is connected to the energy source and madeof a heat-conductive material, e.g., metal. In another embodiment, theinsulated and uninsulated portions are made of essentially the samematerial but somehow sectionalized to be selectively heat-conductivewhen the coil 153 is energized. There are a variety of ways to insulatean otherwise conductive body, e.g., with a non-conductive sleeve orcoating, or embedding a non-conductive barrier (not shown) between theinsulated portion and the uninsulated portion. In one embodiment, anon-thrombogenic polymer half-sleeve or foam coating is applied forinsulation purposes.

Still referring to FIGS. 19A and 19B, in the illustrated embodiment, anelectrode 172 is the uninsulated or exposed portion of the coil middlesection 162, which will contact both the septum primum and the septumsecundum if they are fitted into the coil 153 as described above.Because the coil 153 is configured to position the electrode 172 tocontact the target tissue, in this case, both the septa tissue, the coil153 is a locator in that sense. In one embodiment, the coil 153 isdetachable from the rest of the device, e.g., at point 164. Anyconventional detachable connection can be used for this purpose, e.g.,mechanical threading (not shown).

FIGS. 20 and 21 depict a method of using a coiled welding element forclosing a PFO. Referring first to FIG. 20, the operator advances thecatheter sheath 152 to the heart as described previously, e.g., throughthe inferior vena cava 40 to the right atrium 32, then through the PFO,to the left atrium 30. The operator then deploys the coiled weldingelement 150 out of the catheter sheath 152 as depicted in FIG. 20.

Referring now to FIG. 21, the operator pulls back the catheter sheath152 and the welding element 150 until the sheath tip withdraws into theright atrium 32 and the deployed coil 153 is situated against the septumsecundum 36 and the septum primum 34. The coil distal pitch 168 allowsthe septum primum 34 to be grasped between the distal coil section 159and the middle coil section 162. The coil proximal pitch 170 allows theseptum secundum 36 to fit between the middle coil section 162 and theproximal coil section 166. The operator may need to twist the coil 153in order to engage the septum secundum 36 and the septum primum 34. In apreferred embodiment where the coil 153 is made of Nitinol, when theoperator connects electricity, e.g., RF current, to the coil 153, thecoil 153 further clamps the septum primum 34 against the septum secundum36 as coil 153 increases in stiffness. At the same time, the exposed .electrode 172 starts to heat the tissue it contacts which includes boththe septum primum 34 and septum secundum 36.

After a weld is created between the septum primum 34 and septum secundum36, the operator withdraws the welding element 150 back into thecatheter sheath 152, e.g., by twisting in the counter-clock direction.Alternatively, if withdrawing the coil 153 will cause too much damage tothe tissue, the operator detaches a detachable coil 153 from the rest ofthe welding element 150, leaving the coil 153 embedded in the tissue.Then the operator withdraws the catheter sheath 90 out of the patient.

Variations, modifications, and other implementations of what isdescribed herein will occur to those of ordinary skill in the artwithout departing from the spirit and the scope of the invention. Theinvention is not to be defined only by the preceding illustrativedescription.

What is claimed is:
 1. An intravascular device for treating a septaldefect in a subject, the device comprising: a) a tissue welding element;b) a hollow needle having a sharp distal tip and a proximal anchor andfurther having one or more prongs extending outwardly therefrom toimmobilize the welding element within the septal defect; c) a borebetween the sharp distal tip and the proximal anchor; d) a central cableslidably disposed within the bore, the central cable being attached toan energy source and having a distal pronged anchor to anchor the needlewithin the septal defect.
 2. The device according to claim 1, whereinthe distal anchor of the central cable is movable from an open positionto a clamping position.
 3. The device according to claim 1, wherein thedistal anchor of the central cable is made of a shape memory material.4. A method for treating a septal defect by treating it with the deviceaccording to claim 1, the method comprising applying energy to thetissue surrounding the septal defect from the energy source through thetissue welding element.
 5. The method of claim 4, wherein the septaldefect is a patent foramen ovale, and the tissue welded together is theseptum secundum and the septum primum.